The present invention relates to a treatment agent for elastic polyurethane fibers, and elastic polyurethane fibers treated by using the treatment agent. In more detail, it relates to a treatment agent for elastic polyurethane fibers, which agent is stable in viscosity for a long time during use in the production process of elastic polyurethane fibers allows fiber packages having with good winding form and reelability to be produced if a treatment agent having with a higher fatty acid magnesium salt well dispersed is applied to elastic polyurethane fibers, and which drips less and accumulates less on guides to assure stable operation (fiber passage). The present invention also relates to elastic polyurethane fibers treated by using the treatment agent.
Conventional methods for treating elastic polyurethane yarns include 1) treating by a treatment agent with a higher fatty acid metal salt dispersed in polydimethylsiloxane or mineral oil (JP-B-SHO-37-4586, SHO-40-5557 and HEI-6-15745), 2) treating by a treatment agent with an amino modified silicone added to polydimethylsiloxane or mineral oil (JP-B-SHO-63-8233), 3) treating by a treatment agent with a polyether modified silicone added to polydimethylsiloxane or mineral oil (JP-B-SHO-61-459, and JP-A-HEI-2-127569 and 6-41873), 4) treating by a treatment agent with a silicone resin added to polydimethylsiloxane or mineral oil (JP-B-SHO-42-8438 and 63-12197 and JP-A-HEI-8-74179), 5) treating by a treatment agent with an amino modified silicone and a silicone resin added to polydimethylsiloxane or mineral oil (JP-A-HEI-3-294524, 3-51374 and 5-195442), etc.
In the method of treating an elastic polyurethane yarn by a treatment agent with a higher fatty acid metal salt dispersed in polydimethylsiloxane or mineral oil, the initial dispersed state of the higher fatty acid metal salt cannot be retained, which causes, cohesion, settlement, etc. with the lapse of time. Since a treatment agent has remarkably low dispersion stability like this, the higher fatty acid metal salt coheres even if the treatment agent is sufficiently stirred when used. So, the elastic polyurethane yarn cannot have satisfactory reelability since the overlying segments of the yarn adhere to each other. Furthermore, since the cohering higher fatty acid metal salt drips and accumulates on guides during processing, it causes yarn breaking disadvantageously. Moreover, if a treatment agent having a large amount of a higher fatty acid metal salt dispersed is used, any matter dissolved from the fibers during processing raises the viscosity of the treatment agent after the lapse of time, and disadvantageously, and stable operation cannot be achieved. If a treatment agent with a modified silicone such as an amino modified silicone, polyether modified silicone or silicone resin added to polydimethylsiloxane or mineral oil is used, the effect of preventing the adhesion between yarn segments in an elastic polyurethane resin package is weaker compared to the case of using a treatment with a higher fatty acid metal salt added, and satisfactory reelability cannot be obtained. Especially when a treatment agent containing an amino modified silicone or polyether modified silicone is used for treatment, the inter-fiber friction coefficient becomes very low, and the winding in the package is deformed and no good winding form can be obtained. Furthermore, low molecular components are dissolved out of the fibers, to drip and accumulate as scum on guides with the lapse of time, disadvantageously not allowing stable operation.
An object of the present invention is to provide a treatment agent for elastic polyurethane fibers, which can give excellent winding form and reelability to elastic polyurethane fibers and can decrease the deposition and accumulation of scum on guides during processing, to assure stable operation, and also to provide elastic polyurethane fibers treated by using the treatment agent.
The present invention can provide a treatment agent for elastic polyurethane fibers comprising a dispersion in which a higher fatty acid magnesium salt represented by the following formula I is colloidally dispersed in a silicone mixture consisting of a silicone oil having a viscosity of 5xc3x9710xe2x88x926xe2x88x9250xc3x9710xe2x88x926 m2/S at 25xc2x0 C. as a dispersion medium and a dispersant with a modified silicone as a main ingredient at a ratio by weight of the dispersion medium/the dispersant=100/0.5-100/4.5, wherein the amount of the higher fatty acid magnesium salt is 1 to 10 parts by weight per 100 parts by weight of the silicone oil. 
(R2, R3: an alkyl group with 11 to 21 carbon atoms)